In situ epoxidation of fatty acids



United States Patent IN SITU EPOXIDATION OF FATI'Y ACDS Frank P. Greenspan and Ralph J. Gall, Buffalo, N. Y., assignors, by mesne assignments, to Food Machinery and Chemical Corporation, San Jose, Calif., a corporation of Delaware 'No Drawing. Application March 10, 1954 Serial No. 415,432

3 Claims. 01. 260348.5)

The present invention relates to a method of epoxidizing higher fatter acids containing an ethylenic linkage, and particularly those fatty acids obtained from fatty oils which contain oleic acid. The epoxidation is performed with hydrogen peroxide, acetic acid, and a small amount of sulfuric acid in the presence of an organic solvent and at a relatively high temperature. A similar method of epoxidation, but applied particularly to esters of unsaturated higher fatty acids is disclosed in our co-pending application Serial No. 367,752, filed July 13, 1953.

Heretofore, in the principal method of epoxidizing unsaturated fatty acids,such as oleic acid, a prepared peracetic acid solution has been employed as the peroxidizing reagent. Such solutions are generally equilibrium mixtures of hydrogen peroxide and peracetic acid with substantial amount of free peroxide present. Under the reaction conditions employed for such epoxidation, substantially only the peracid fraction of the equilibrium mixture is utilized. There is little or no further formation of peracid from the free peroxide present and this free peroxide is unused; this is extremely wasteful, as much as 20% of the available active oxygen remaining unutilized. Accordingly, reaction. techniques, wherein hydrogen peroxide and lower aliphatic acids are caused to react upon the unsaturated fatty acid, have long been sought, for direct epoxidation reactions. Such techniques are standard for hydroxylation reactions with hydrogen peroxide.

Despite the recognized attraction of such an epoxidation proceduce, little progress has been made in its fulfillment because of the extreme difficulty of setting up reaction conditions favorable to the required peracid formation from the peroxide and lower aliphatic acid, which simultaneously would not destroy the desired end product, the formed epoxy derivative. It is to be noted that the very same conditions favoring peracid formation from aliphatic acid and hydrogen peroxide, notably high molar ratios of aliphatic acid to H high temperatures, high acidity, long reaction times, are known to be deleterious to the survival of any epoxy compound.

Epoxy fatty acids containing oleic acid find application as valuable intermediates in making lubricants, lubricant additives, stabilizers, plasticizers, resins, textile oils, etc.

In epoxidation reactions, the desirable end product is one containing the group:

the so-called oxirane group, in preference to a hydroxylated precursor of a product of the following structure:

-HC-OH- oil (.11 or a so-called glycol.

The process described herein, wherein the unsaturated higher fatty acid is reacted directly with hydrogen peroxide in the presence of acetic acid and a small quantity of sulfuric acid, has the great advantage of producing as co-product only small amounts of a relatively cleavage resistant acetoxy derivative.

It is an object of the present invention to provide a" process for manufacturing epoxidized higher fatty acids by the employment of hydrogen peroxide and acetic acid rather than peracetic acid.

It is also object of the invention to prepare snch epoxidized higher fatty acids in extremely short periods of time.

It is a further object of the invention to prepare such epoxidized higher fatty acids without the necessity of employment a prepared peracetic acid.

It is a further object to provide an economical process for epoxidation.

It is a further object to provide a safe controllable epoxidation reaction.

It is further object to provide a process allowing for ready recovery of the aliphatic acid used.

In the broad aspect of the invention, an unsaturated higher fatty acid, that is to say, an acid containing from 16 to 22 carbon atoms, is reacted at temperatures between about 50 C. and 100 C. with hydrogen peroxide, acetic acid and a small amount of sulfuric acid, for a period of time of from 1 hour to 10 hours.

The reaction is performed in the presence of an inert organic solvent, such as benzene, hexane, and the like, the purpose of which is to dissolve the fatty acid and provide a better reaction environment.

The presence in the reaction mixture of from about l/2% to 5% sulfuric acid, based upon the combined weight of acetic acid and aqueous hydrogen peroxide,

is a requirement of the invention in order to obtain high yields of oxirane oxygen at the elevated temperatures and dized. A slight excess will generally be employed to assure complete reaction. The epoxidation reaction of the present inventio when employing acetic acid and hydrogen peroxide, proceeds smoothly only in the presence of sulfuric acid. In the absence of sulfuric acid, the yields of oxirane product are low.

The advantage of performing the process in the presence of 1/2% to 5% sulfuric acid, resides in the pro-- duction not only of the very high proportion of oxirane product, but also the very high proportion of double bond reacted upon.

The amount of sulfuric acid present appears to control the percent epoxidation and, in some fashion, to enter into the mechanism of the epoxidation. Where the quantity of sulfuric acid is low, the epoxidation is not complete and the epoxy compound production poor. it is generally perferred to employ from about 1% to 5% sulfuric acid. 7

The following examples are given merely as illustrative of the invention and not as limitative of the conditions, as the broad ranges have been stated above, it being understood that the reaction is of particular applicability for the epoxidation of higher fatty acids containing oleic acid, such as the fatty acids obtained from fatty oils.

Example 1 100 g. of a commercial fatty acid containing oleic acid, together with other unsaturated fatty acids (iodine number 92, equivalent to 0.362 mole of ethylenic unsaturation) were weighed into a three-neck flask equipped with a reflux condenser, thermometer and mechanical Patented Oct. 22,

As the source of oxygen, the hydrogen peroxide stirred 100 gfof hexane, 10.85 g., of glacial acetic acid (0.181 mole) and 1.6 1 g. of50% sulfuric acid were 7 added and the mixture. warmed to 50 C. Then 29.52 g. of ;5 H202 (0.434 ;mole) were:s low1y added over hour period The temperature was then raised; to. 60." .C.: and maintained betweeii'ot) to 65? .C. for an -ad-' ditional 4 6 hours. The reaction mixture 'was pofired.

lm eaw erenne a sith fla -wa are dre 0 Thepil layerwas-washed with warm-water until free of acetic acid. The solvenfand traces of water wereremoved in ,a vacuum stripping column at 60 to 70." C. at

a pressure of to 10 millimeter o f rnereur y. The crystalliz'ed product obtained was analyzed and found to contain:

Percent. oxirane oxygen-.5... per'c'en't 4.1

'(Thcoretical 5.5%) 1 Iodine number 6.4 Acid numberin 180.

Example 2 were slowly added 'over a /2 hour period. The'temperature was then raised to 60 C. and maintained between 60;to 65C. for anadditional 5 hours. The reaction mixture. was poured into a separatory funnel and the'aqueous layer drawn off. The oil layer was washed with warm water until free of acetic acid. The solvent and traces of water were removed in a vacuum strip ping eolumn at 60 to 70 C. at a pressure of 5 to 10 millimeter of mercury. tained was analyzed and found to contain:

The crystallized product ob- 1 acid, aqueous hydrogen peroxide and sulfuric acid to said Percentjoxirane oxygen percent 2.9 (Theoretical5 .5 I Iodine number 12.8 Acid number 1 174 'Example 3 100 g. of a commercial soybean oil fatty acid containing about 2 6% oleic acid together with other unsaturated fatty acids (iodine number 120, equivalent to 0.472 mole -or" e'thylenic unsaturation) were weighed into a threeneck flask equipped witha. reflux'condenser, thermometer and mechanical stirrer. 100 g. of benzene, 14.2 g. of glacial acetic acid (0.236 mole) and 2,1 g. of sulfuric acid were added and the mixture warmed to between -to 65 C. Then 38.59 g. of 50% H202 (0.568

mole)"were slowly added over a l hour period. The temperature was then maintained between to, C. for an additional 6 hours. The reaction mixture was 'poured into'aseparatory'funnel and the aqueous layer drawn" off. The oillayer was washed with warm water until free of acetic acid. The solvent and traces of water were removed in a vacuum stripping column at 60 to C. at a pressure of 5 to 10 millimeter of mercury. The

crystallized product obtained was analyzed and found to contain:

Percent oxirane oxygen percent 3.1

(Theoretical--7.04%

Iodine .number aa 11.1

Acid number .1 What is claimed is: j 1. The method. of epoxidizing an unsaturated higher; fatty acid containing oleic acid which comprises adding an inert-organichydrocarbon' solvent, acetic acid, aqueous hydrogen peroxide and sulfuric acid to said fatty acid and heating the reaction mixture to substantially-50 to C. and maintaining this temperature, during the epoxidation reaction, the amount of acetic acid being 0.25 mole to 1 mole per moleofethyle'nic unsaturation to be reacted, the amount of sulfuric acid being between 0.5 and 5% by weight basedjupon the weight of acetic acid and aqueous hydrogen peroxideemployed, and the;

amount of aqueous hydrogen peroxide being sufiicient t oprovide approximately one mole of hydrogen peroxide per mole of ethylenic unsaturation acid to be reacted. v a 1 2. The method of epoxidizing an unsaturated higher;

in said higher fatty;

fatty acid containing oleic acid which comprises adding an; inert organic hydrocarbon solvent, acetic acid and sulfl furic acid to said fatty acid and then adding hydrogen; peroxide thereto slowly and heating the reaction mix ture to substantially 50 to 100 C. and maintaining this; temperature duringthe epoxidation reaction, the amount of sulfuric acid being between 0.5 and 5% by weight based upon the weight of aceticacid and aqueous hydrogen peroxide employed, and the amount, of hydrogenperoxide being approximately one mole per mole of eth ylenic .unsaturation in said unsaturated higher fatty acid, to be reacted. :3. The method of epoxidizing oleic acid which com prises adding an inert organic hydrocarbon solvent, acetic 5 fatty acid and heating the reaction mixture to substan daily 50 to 100- C. and maintaining this temperature dur-- ing the epoxidation reaction, the amount of acetic acid being 0.25 mole to 1 mole per mole of ethylenic unsaturation to be reacted, the amount of sulfuric a'cidbe ing' between 0.5 and 5% by .weight'based upon the weight of acetic acid and aqueous hydrogen peroxide employed;

and the amount of aqueous hydrogen peroxide being suf-' ,ficint, to provide approximately one mole of hydrogen.

peroxide per mole of ethylenic unsaturation in saturated higher fatty acid to be reacted.

References Cited in -the file of'this patent UNITED STATES PATENTS said un- 2,485,160 Niederhauser oct. 18,1949 1 2,567,930 Findley. Sept. 18, 1951,

Swern Oct. 2, 1951 OTHER'REFERENCES- I MacArdle; Use of Solvents, pp.13,'Van Nostrand Co. (1925). W

Findley: J. Amer. Chem. Soc, Mar. 1945, vol. 67, pp:

412-14. Swern: J. American Chemical Society, vol. 67, Oct. 1946, p. 1786.

Swern: Chemical Reviews, vol. 45, Aug. 1949, pp; 

1. THE METHOD OF EPOXIDIZING AN UNSATURATED HIGHER FATTY ACID CONTAINING OLEIC ACID WHICH COMPRISES ADDING AN INERT ORGANIC HYDROCARBON SOLVENT, ACETIC ACID, AQUEOUS HYDROGEN PEROXIDE AND SULFURIC ACID TO SAID FATTY ACID AND HEATING THE REACTION MIXTURE TO SUBSTANTIALLY 50 TO 100*C. AND MAINTAINING THIS TEMPERATURE DURING THE EPOXIDATION REACTION, THE AMOUNT OF ACETIC ACID BEING 0.25 MOLE TO 1 MOLE PER MOLE OF ETHYLENIC UNSATURATION TO BE REACTED, THE AMOUNT OF SULFURIC ACID BEING BETWEEN 0.5 AND 5% BY WEIGHT BASED UPON THE WEIGHT OF ACETIC ACID AND AQUEOUS HYDROGEN PEROXIDE EMPLOYED, AND THE AMOUNT OF AQUEOUS HYDROGEN PEROXIDE BEING SUFFICIENT TO PROVIDE APPROXIMATELY ONE MOLE OF HYDROGEN PEROXIDE PER MOLE OF ETHYLENIC UNSATURATION IN SAID HIGHER FATTY ACID TO BE REACTED. 